JP2010014701A - Array-type magnetic sensor substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an array-type magnetic sensor substrate that does not require a large system for calibration of dynamic detection sensitivity and is easily calibrated. <P>SOLUTION: This array-type magnetic sensor substrate 10 includes a printed board 1, an array-type magnetic sensor 2 arranged linearly on one surface of the printed board, a pattern line 4 printed and molded on the plane of the printed board, on one side or both sides of right and left string axes of the array-type magnetic sensor, in parallel with the string axes, and at a predetermined interval, and a pulsed current generating circuit 3 for making a predetermined pulsed current flow to the pattern line. A reference magnetic field during calibration is generated by making the pulsed current flow to the pattern line, and the detection sensitivity of the array type magnetic sensor is calibrated. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an array-type magnetic sensor substrate used in an array-type magnetic flaw detector or the like that detects the presence or absence of a defect from a leakage magnetic flux generated by a defect in a thin steel plate, and in particular, an array that facilitates calibration of the array-type magnetic sensor. The present invention relates to a type magnetic sensor substrate.

  Conventionally, as a device for detecting the surface layer of a tin plate (herein referred to as thin steel), which is a material for food cans, and the like, and a minute defect existing inside, a plurality of array-type magnetic sensors are used. There is an array-type magnetic flaw detector that is arranged in the direction and detects the leakage magnetic flux generated by the defect to determine the presence or absence of the defect (for example, see Patent Document 1).

  The configuration of the magnetic sensor head 30 of this array type magnetic flaw detector is shown in FIG. As shown in FIG. 3A, the magnetic sensor head 30 has an opening portion of an inverted U-shaped magnetizing yoke 24 that is in close contact with the surface of the thin steel plate 13 that is pressed against the surface of the nonmagnetic roll 11 and conveyed in the direction of the arrow. Further, a predetermined gap (herein referred to as lift-off) is provided with the thin steel plate 10, and the thin steel plate 13 is magnetized in the traveling direction by a magnetizer including a magnetizing yoke 24 and a magnetizing coil 22 wound around the magnetizing yoke 24. For shaping the magnetic field.

  And in this opening part, it is made to adjoin to the thin steel plate 13 by the preset lift-off, and the semiconductor magnetic sensor 12 such as a Hall element for detecting the leakage magnetic flux generated in the defective portion of the thin steel plate 13, and the semiconductor magnetic sensor 12 A soft magnetic body 14 for improving sensitivity is provided, and the leakage magnetic flux from the thin steel plate 13 intensively crosses the sensitive surface of the semiconductor magnetic sensor 12 in the vertical direction so that the presence or absence of minute defects is highly sensitive. It is detected by.

  For example, as shown in FIG. 3B, the semiconductor magnetic sensor 12 has a large number of magnetic sensors (elements) so as to ensure a predetermined resolution in the width direction linearly in the width direction of the thin steel plate 13. Are arranged in a straight line at equal intervals.

  The semiconductor magnetic sensor 12 is periodically calibrated in order to make the detection sensitivity in the width direction of each magnetic sensor (element) uniform and to ensure defect detection accuracy.

  In the magnetic sensor head 30 using such an array type magnetic sensor, a calibration device 20 as shown in FIG. 4A has been conventionally used (for example, refer to Patent Document 2).

  In the calibration device 20, when the semiconductor magnetic sensor 12 is calibrated, the arrangement direction of the semiconductor magnetic sensor 12 and the tangential surface of the nonmagnetic roll 11a are arranged to face each other, and the conducting wire 11b is arranged on the surface facing the nonmagnetic roll 11a. And a current generator 15 is applied to the conducting wire to generate a predetermined magnetic field.

  Then, in this state, the motor 11b connected to the nonmagnetic roll 11a is driven to rotate the nonmagnetic roll 11a as shown in FIG. 4B, and the semiconductor based on the magnetic field based on the applied current as a reference magnetic field. The magnetic sensor 12 is calibrated.

  However, in the calibration shown in Patent Document 2, since the conducting wire 11 b faces the row of the semiconductor magnetic sensors 12, the magnetic field from the conducting wire is parallel to the magnetic sensitive surface of the semiconductor magnetic sensor 12.

  For this reason, when trying to calibrate the detection sensitivity using a magnetic field perpendicular to the magnetic sensitive surface of the semiconductor magnetic sensor 12, the problem is that the magnetic field in the vertical direction that is actually used cannot be applied to the semiconductor magnetic sensor 12. Furthermore, there is a problem that the calibration device 11 becomes large-scale, such as preparing a large rotating roll. (Hereinafter, the semiconductor magnetic sensor 12 is referred to as an array type magnetic sensor herein.)

  Therefore, when calibrating an array type magnetic sensor having one or more columns of a plurality of array type magnetic sensors, the conductor is a method of the center line of the array type magnetic sensor column and the magnetic sensitive surface of the array type magnetic sensor. An array type that is arranged in parallel to the array type magnetic sensor array at a position other than the plane formed by the line, generates a magnetic field by flowing a predetermined current through the conductor, and uses the magnetic field as a reference magnetic field A magnetic sensor calibration method is disclosed (for example, Patent Document 3).

  However, in the calibration device in Patent Document 3, although the perpendicular magnetization can be efficiently applied to the magnetic sensitive surface of the magnetic sensor, the dynamic detection sensitivity for a minute defect of the thin steel plate, that is, the thin There is a problem that the detection sensitivity cannot be calibrated in the running state of the steel plate.

  Therefore, when trying to calibrate the dynamic detection sensitivity (at the maximum moving speed of the thin steel plate) for minute defects of individual magnetic sensors, a large calibration device as shown in Patent Document 2 is still necessary. There is a problem.

  Therefore, as shown in FIG. 5, the inventor of the present application applies a calibration sample plate 32 having a conductor wound around a non-magnetic material plate once in a straight line, and a magnetic sensing surface of the array type magnetic sensor 12. With a predetermined lift-off, a pulse current is applied to the sample support 33 having a moving mechanism for finely adjusting the position of the calibration sample plate 32 in the moving direction of the thin steel plate on a plane parallel to the magnetosensitive surface and the conductor 32a. A pulse current generator 34, a pulse current having a pulse width Pw and a pulse peak value Ph is passed through the conductor 32a, a pulse magnetic field is applied to the array type magnetic sensor 12, and the detection sensitivity of the dynamic magnetic sensor is calibrated. An array-type magnetic flaw detection apparatus calibration apparatus 40 is disclosed (see, for example, Patent Document 4).

Japanese Patent No. 3811039 (FIG. 1, page 1) Japanese Patent Laid-Open No. 9-229905 (FIG. 1, page 1) Japanese Patent Laying-Open No. 2005-61940 (FIG. 1, page 1) Japanese Patent Laying-Open No. 2009-14678 (FIG. 1, page 1)

  In the calibration device in Patent Document 4, the dynamic detection sensitivity of a thin steel plate can be calibrated by applying a pulse current to the magnetic sensitive surface of the array type magnetic sensor 12.

  However, on a flat plate parallel to the magnetic sensitive surface with a predetermined lift-off relative to the magnetic sensitive surface of the array type magnetic sensor, or a calibration sample plate having a conductor wound around the non-magnetic material plate once in a straight line. Therefore, there is a problem that a sample support base having a moving mechanism for finely adjusting the position of the calibration sample plate in the moving direction of the thin steel plate is necessary, and the size of the apparatus cannot be avoided.

  The present invention has been made to solve the above problems, and is an array type magnetic sensor substrate having one or a plurality of array type magnetic sensors on a printed circuit board. Therefore, it is an object of the present invention to provide an array type magnetic sensor substrate that does not require a large apparatus and can be easily calibrated.

  In order to achieve the above object, an array type magnetic sensor substrate according to the present invention includes an array type magnetic sensor having a plurality of magnetic sensors arranged in a line on a printed circuit board. The array-type magnetic sensor substrate includes: the printed circuit board; an array-type magnetic sensor arranged linearly on one surface of the printed circuit board; On one side or both sides, a conductor fixed to the printed circuit board at a predetermined interval in parallel with the column axis, and a pulse current generating circuit for supplying a predetermined pulse current to the conductor, the conductor including the A reference magnetic field at the time of calibration is generated by flowing a pulse current, and detection sensitivity calibration of the array type magnetic sensor is performed.

  According to the present invention, an array type magnetic sensor substrate having one or a plurality of array type magnetic sensors on a printed circuit board, which eliminates the need for a large-sized device for dynamic detection sensitivity calibration and facilitates calibration. It is possible to provide an array type magnetic sensor substrate that can be used in a simple manner.

The array type magnetic sensor substrate of the present invention. The figure explaining the setting principle of the pulse current of this invention. The figure explaining the conventional magnetic sensor head. The figure explaining the conventional calibration apparatus. The figure explaining the calibration device of the conventional array type magnetic flaw detector.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows a configuration of an array type magnetic sensor substrate 10. FIG. 1A is a plan view, and FIG. 1B is a cross-sectional view as seen from the direction indicated by the arrow y-y ′.

  The array type magnetic sensor substrate 10 includes a printed circuit board 1, an array type magnetic sensor 2 including a plurality of magnetic sensors arranged linearly on one surface of the printed circuit board 1, and the left and right sides of the column axis of the array type magnetic sensor 2. The pattern line 4 printed and formed on the plane of the printed circuit board 1 at a predetermined interval in parallel with the column axis on either one side or both sides of the pattern line 4 and a pulse current for applying a predetermined pulse current to the pattern line 4 And a generation circuit 3.

  The setting of the pulse current will be described with reference to FIG. When the current I is applied to the finite-length pattern line 4, the magnetic flux density B generated at the point P that is separated from the pattern line 4 by the vertical distance R is in the case of a geometrical positional relationship as shown in FIG. From the Biosavall's law, the following formula is obtained.

B = μ ₀ · I · (cos θ ₁ + cos θ ₂ ) / (4π · R)
Therefore, the conductor current giving the magnetic flux density B of the reference magnetic field is
I = B · 4πI · R / [μ ₀ · (cos θ ₁ + cos θ ₂ )]
Is required.

Here, μ ₀ is the magnetic permeability of vacuum, θ ₁ is an angle formed by a straight line connecting the point P and the left end of the pattern line 4 with respect to the pattern line 4, and θ ₂ is a point P with respect to the pattern line 4. This is an angle formed by a straight line connecting the right end of the pattern line 4.

  Actually, since the pattern line 4 has a finite length, as shown in FIG. 2B, an excessive current is required to supply a magnetic field similar to that at the central portion at both ends of the array type magnetic sensor. Become. Therefore, the pattern line 4 is made sufficiently longer than the array type magnetic sensor 2 so as to be within the variation of the allowable magnetic field intensity.

  For example, when used for flaw detection of minute defects in a thin steel plate, the array type magnetic sensor 2 is composed of a commercially available Hall element, and the plane distance R between the magnetic sensitive surface of the Hall element and the pattern line 4 is 2 mm. When the magnetic flux density B at the time of calibration is 1 mT, the applied current is about 10A.

  When two conductors are provided on both sides of the column axis of the array type magnetic sensor 2 as shown in FIG. 1 and currents applied in opposite directions are added to each other, the current becomes about 5 A per conductor. . This current value can be a pulse current with a magnetic field to be calibrated of about several milliseconds, so that the pattern line 4 can be supplied only by the pattern line on the printed circuit board without taking any special heat dissipation measures. It is.

  In addition, since the position of the array type magnetic sensor 2 and the conductor 4 that generates the magnetic field to be applied can be accurately fixed in advance on the printed circuit board 1, a uniform calibration magnetic field can be applied to the array type magnetic sensor 2 as in the past. Therefore, a calibration device including a fine adjustment mechanism for the position of the magnetic field generation device and the magnetic sensitive surface of the array type magnetic sensor 2 or a large rotation mechanism for generating a dynamic magnetic field is not necessary.

  When a large current is required, a conductor such as a bus bar formed of a metal such as copper whose position is accurately fixed to the array type magnetic sensor 2 instead of the pattern line may be fixed on the printed circuit board. good.

  In addition to downsizing the calibration device, it is possible to apply a dynamic magnetic field to each of the array type magnetic sensors 2 at the same time, so that accurate calibration can be performed in a short time.

  The present invention is not limited to the embodiment described above, and a plurality of array type magnetic sensors may be provided, and the pattern line 4 through which the pulse current flows is optimal depending on the required calibration magnetic field conditions. The cross-sectional shape and the waveform of the required calibration magnetic field may be arbitrarily generated as a pulse current waveform, and as appropriate within the scope of the present invention depending on the conditions required for the target detection magnetic field. It is possible to change.

DESCRIPTION OF SYMBOLS 1 Printed circuit board 2 Array type magnetic sensor 3 Pulse current generation circuit 4 Pattern line 10 Array type magnetic sensor board | substrate 11, 11a Nonmagnetic roll 11b Conductor 11c Motor 15 Current generator 20 Calibration apparatus 12 (Semiconductor magnetic sensor) Array type magnetic sensor 13 Strip 14 Soft magnetic material 15 Thin steel plate 22 Magnetizing coil 24 Magnetizing yoke 30 Magnetic sensor head 32 Calibration sample plate 32a Conductor 33 Sample support 33a Moving mechanism 34 Pulse current generator 40 Calibration device

Claims (3)

An array type magnetic sensor substrate having one or a plurality of array type magnetic sensors formed by arranging a plurality of magnetic sensors in a line on a printed circuit board,
The array type magnetic sensor substrate includes the printed circuit board,
An array type magnetic sensor arranged linearly on one surface of the printed circuit board;
A conductor fixed to the printed circuit board at a predetermined interval in parallel with the column axis on either one of the left and right sides of the column axis of the array type magnetic sensor, or both sides,
A pulse current generation circuit for supplying a predetermined pulse current to the conductor;
An array type magnetic sensor substrate, wherein the pulse current is passed through the conductor to generate a reference magnetic field at the time of calibration, and the detection sensitivity of the array type magnetic sensor is calibrated. The conductor is a pattern line printed and formed on the plane of the printed circuit board at a predetermined interval in parallel with the column axis on either one or both sides of the column axis of the array type magnetic sensor. ,
2. The array type magnetic sensor substrate according to claim 1, wherein the pulse current is passed through the pattern line to generate a reference magnetic field at the time of calibration, and detection sensitivity calibration of the array type magnetic sensor is performed. The array type magnetic sensor substrate according to claim 1, wherein the conductors are arranged at left and right positions equidistant from the column axis center of the array type magnetic sensor, and pulse currents in opposite directions flow.

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